CAMP DAVID, Md.--President Joe Biden and the leaders of Japan and South Korea agreed Friday to expand security and economic ties at a historic summit at the U.S. presidential retreat of Camp David, cementing a new agreement with the allies that are on an increasingly tense ledge in relations with China and North Korea.

Biden said the nations would establish a communications hotline to discuss responses to threats. He announced the agreements, including what the leaders termed the “Camp David Principles,” at the close of his talks with South Korean President Yoon Suk-yeol and Japanese Prime Minister Fumio Kishida.

“Our countries are stronger and the world will be safer as we stand together. And I know this is a belief that all three share,” Biden said.

“The purpose of our trilateral security cooperation is and will remain to promote and enhance peace and stability throughout the region,” the leaders said in a joint statement.

Biden maintained, as have U.S., South Korean and Japanese officials, that the summit “was not about China” but focused on broader security issues. Yet, the leaders in their joint summit concluding statement noted China’s “dangerous and aggressive” action in the South China Sea and said they “strongly oppose any unilateral attempts to change the status quo in the waters of the Indo-Pacific.”

Yoon noted in particular the threat posed by North Korea, saying the three leaders had agreed to improve “our joint response capabilities to North Korea’s nuclear and missile threats, which have become sophisticated more than ever.”

He said as the three appeared before reporters that “today will be remembered as a historic day, where we established a firm institutional basis and commitments to the trilateral partnership.”

Kishida said before the private talks that “the fact that we, the three leaders, have got together in this way, I believe means that we are indeed making a new history as of today. The international community is at a turning point in history.”

The visitors spoke in their home languages, their comments repeated by a translator.

The United States, Japan and South Korea agreed to a new “duty to consult” security pledge committing them to speak with each other in the event of a security crisis or threat in the Pacific.

The pledge is intended to acknowledge that they share “fundamentally interlinked security environments” and that a threat to one is “a threat to all,” according to a senior Biden administration official. 

Under the pledge, the three countries agree to consult, share information and align their messaging with each other in the face of a threat or crisis, the official said.

The Camp David retreat, 105 kilometers from the White House, was where President Jimmy Carter brought together Egyptian President Anwar Sadat and Israeli Prime Minister Menachem Begin in September 1978 for talks that established a framework for a historic peace treaty between Israel and Egypt in March 1979. In the midst of World War II, President Franklin Roosevelt and British Prime Minister Winston Churchill met at the retreat--then known as Shangri-La--to plan the Italian campaign that would knock Benito Mussolini out of the war.

Kishida and Yoon were mindful of Camp David’s place in U.S. and world history, making repeated references to its past and now their place in it during their comments at the news conference after the meeting with Biden. 

Biden’s focus for the gathering was to nudge the United States’ two closest Asian allies to further tighten security and economic cooperation with each other. 

The effort to sustain the trilateral relationship won’t be without challenges.

Beijing sees the tightening cooperation efforts as the first steps of a Pacific-version of NATO, the transatlantic military alliance, forming against it. U.S. officials expect that North Korea will lash out--perhaps with more ballistic missile test and certainly blistering rhetoric.

Biden’s predecessor (and potential successor) Republican Donald Trump unnerved South Korea during his time in the White House with talk of reducing the U.S. military presence on the Korean Peninsula.

“If an ultra-leftist South Korean president and an ultra-right wing Japanese leader are elected in their next cycles, or even if Trump or someone like him wins in the U.S., then any one of them could derail all the meaningful, hard work Biden, Yoon and Kishida are putting in right now,” said Duyeon Kim, an adjunct senior fellow at the Center for a New American Security’s Indo-Pacific Security Program.